AUTHOR=Li Yue , Zhang Jihui , Zheng Jiazhen , Guan Hanye , Liu Wen , Tan Huarong 

TITLE=Co-expression of a SARP Family Activator ChlF2 and a Type II Thioesterase ChlK Led to High Production of Chlorothricin in Streptomyces antibioticus DSM 40725

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2020.01013

DOI=10.3389/fbioe.2020.01013

ISSN=2296-4185

ABSTRACT=<p>Chlorothricin (CHL), produced by <italic>Streptomyces antibioticus</italic> DSM 40725 (wild-type strain, WT), belongs to a growing family of spirotetronate antibiotics that have biological activities inhibiting pyruvate carboxylase and malate dehydrogenase. ChlF2, a cluster-situated SARP regulator, can activate the transcription of <italic>chlJ</italic>, <italic>chlC3</italic>, <italic>chlC6</italic>, <italic>chlE1</italic>, <italic>chlM</italic>, and <italic>chlL</italic> to control CHL biosynthesis. Co-expression of <italic>chlF2</italic> and <italic>chlK</italic> encoding type II thioesterase in WT strain under the control of P<italic><sub><italic>kan</italic></sub></italic> led to high production of chlorothricin by 840% in comparison with that of WT. Since the inhibitory activity of CHL against several Gram-positive bacteria is higher than des-CHL, combinatorial strategies were applied to promote the conversion of des-CHL to CHL. Over-expression of <italic>chlB4</italic>, encoding a halogenase, combining with the supplementation of sodium chloride led to further 41% increase of CHL production compared to that of F2OE, a <italic>chlF2</italic> over-expression strain. These findings provide new insights into the fine-tuned regulation of spirotetronate family of antibiotics and the construction of high-yield engineered strains.</p>